Completed Projects

The need for low cost, multi-hazard resilient buildings constructed of sustainable, low-carbon footprint materials is urgent. Mid-rise buildings framed from thin-walled, cold-formed steel (CFS) have the ability to support this urgent need. The potential benefits of CFS-framed structures include low installation and maintenance costs, high durability and ductility, lightweight framing, and use of a non-combustible material. By using framing schemes with closely-spaced vertical members repetitively placed in the walls, CFS buildings develop lateral resistance through sheet, or sheathing attached to these vertical members. The response of these building systems under earthquake loads and, in particular, the contribution of portions of the building system not specifically designated by the design engineers to resist earthquake loads are not well understood. In this project, a series of experiments and complementary numerical modeling to characterize the relationship between the designated lateral force resisting system, i.e., the shear walls, and the complete CFS building system response, including the impact of the gravity walls, finish materials, and interior partitions, during seismic events./p>
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Seismic design codes have to ensure that buildings have a low probability of collapse in the event of a severe earthquake. To develop such standards, the ability to assess the collapse margin ratios of building systems designed according to given specifications is of critical importance. Under severe seismic forces, reinforced masonry (RM) wall structures may develop complicated nonlinear behavior involving interaction between steel and masonry. Furthermore, the interaction of structural walls with other elements in a building system could lead to nonlinear behavior and collapse mechanisms that were not anticipated in design, including behavior dominated by diagonal shear cracks. The ability of analytical models to capture these mechanisms and interactions is crucial for an accurate assessment of the collapse potential of a building. The main aim of this project is to obtain necessary experimental data to understand the behavior of RM wall structures to the point of collapse, and to use the data to advance and validate refined as well as simplified analytical modeling methods.

Development and Validation of a Resilience-based Seismic Design Methodology for Tall Wood Buildings: Phase I Test

With global urbanization trends, the demands for tall residential and mixed-use buildings in the range of 8~20 stories are increasing. One new structural system in this height range are tall wood buildings which have been built in select locations around the world using a relatively new heavy timber structural material known as cross laminated timber (CLT). However, the majority of existing tall CLT buildings are located in non-seismic or low-seismic regions of the world. There is consensus amongst the global wood seismic research and practitioner community that tall wood buildings have a substantial potential to become a key solution to building future seismically resilient cities. The Vision of this project is to develop and validate a seismic design methodology for tall wood buildings that incorporates high-performance structural and nonstructural systems and can quantitatively account for building resilience. This will be accomplished through a series of research tasks planned over a 4-year period. These tasks will include mechanistic modeling of tall wood buildings with several variants of post-tensioned rocking CLT wall systems, fragility modeling of structural and non-structural building components that affect resilience, full-scale biaxial testing of building sub-assembly systems, development of a resilience-based seismic design (RBSD) methodology, and finally a series of full-scale shaking table tests of a 10-story CLT building specimen to validate the proposed design. The project will deliver a new tall building type capable of transforming the urban building landscape by addressing urbanization demand while enhancing resilience and sustainability.

The Phase I tests of this project include a biaxial loading test at NHERI@ Lehigh and a two-story full scale building test at NHERI@UCSD. The two-story shake table test includes a wood building prototype with open floorplan, resilient rocking wall system, and high aspect ratio CLT floor diaphragms.

UCSD-CEMCO / Sureboard-HUD Research Partnership

Abstract: Light-gauge cold-formed steel (CFS) framed multi-story residential housing has the potential to support societies urgent need for low cost, multi-hazard resilient housing. CFS-framed structures offer lower installation and maintenance costs, are durable, ductile, lightweight, and manufactured from recycled materials. In addition, consistency in material behavior and low material costs are added benefits compared with their wood-framing counterparts. The components of CFS-framed assemblies (studs, track, joists) can be assembled quickly and with relative ease into prefabricated panels. Notably, the ductile nature of a CFS-framed structure aligns with the performance needs in moderate to high seismic zones. Compared to other lightweight framing solutions (such as timber), CFS is non-combustible, an important basic characteristic to prohibit fire spread. Taken in totality, these many beneficial attributes lead to a highly sustainable infrastructure for housing communities.

Spillway Retaining Wall Shake Table Test Program 2016

This research aims ultimately to provide seismic performance of a spillway based on experimentally validated engineering procedures with variation of topographical ground conditions. The research work involves intensive dynamic tests for the steel spillway specimen (3.3 ft height, 6 ft width, and 9 ft long in model scale). This spillway is buried in the laminar soil shear container. Dimensions of the container are a length of 22 ft, a width of 9.6 ft, and a height of 11 ft. The spillway and soil will be extensively instrumented to acquire measurements of accelerations, displacements, strains, earth/soil pressures, etc, during the shaking. Each soil-foundation system will be tested under a series of earthquakes starting with slow motions with low amplitude and culminating with two earthquake motions (Northridge and Takatori records).

Abstract: Helical piles are deep foundation elements that look like, and are installed like, a large steel soil screw – they have a slender steel shaft with any number of round plates at the tip to provide support to the structure they hold. Helical piles are spun into the ground with a large torque motor and provide support through soil bearing on the plates and along the shaft. They come in many lengths and are often the foundation of choice for retrofitting existing buildings or new, urban construction, due to their small footprint and ability to create minimal disturbance to surrounding structures. Although helical piles are installed as foundation elements in seismically active areas such as New Zealand and Japan, they have not been used widely in seismically active areas of the United States. This lack of use is, admittedly, due to having no quantifiable data to illustrate the seismic behavior of helical piles. In addition, there are no side-by-side seismic comparisons to other deep foundation systems available, other than qualitative "survival" stories like those from the 2011 Christchurch earthquake.

Seismic Design Guidelines of Cut-and-Cover Tunnel (2015)

Project Description: The objective of the research project is to develop improved and validated rational guidelines for seismic design of cut-and-cover tunnels to overcome the drawbacks in the existing Caltrans design specification and tools. The research work involves intensive dynamic tests for the 1/9 scale steel tunnel specimen (4 ft height, 6 ft width, and 9 ft long in model scale), that is adopted from the Doyle Drive Battery Tunnel (reinforced concrete structure, San Francisco, CA). The tunnel model is fully buried at shallow depth (2 ft) in dry soil using a large scale laminar soil shear container, funded by the California Department of Transportation. The container consists of 31 steel laminar frames, each separated by a steel roller system to allow for uni-directional displacement. Dimensions of the container are a length of 22 ft, a width of 9.6 ft, and a height of 15.2 ft. The tunnel and soil will be extensively instrumented to acquire measurements of accelerations, displacements, strains, earth/soil pressures, etc, during the shaking. Each soil-foundation system will be tested under a series of earthquakes starting with slow motions with low amplitude and culminating with severe earthquake motions (e.g., Northridge record, M=6.7). The outcome of this research will ensure that future cut-and-cover tunnels are designed to a higher performance standard and existing systems are upgraded to offer satisfactory performance.

Although traditional framed residential structures provide a high level of life safety during an earthquake, their vulnerability to damage can be very costly. After the 1994 Northridge Earthquake, it was estimated that $20 billion were issued in insurance payouts for damaged residences. In addition, over 60,000 people were displaced from their homes for a significant period of time. In order to reduce the damage seen by these structures, the current design standards must be revised to prevent the ultimate load from being reached at large damaging drifts..

Reinforced masonry constitutes about 10% of all low-rise buildings in the US. Many of them are commercial, industrial, and school buildings. While most of the reinforced masonry structures constructed in the West Coast are fully grouted, almost all reinforced masonry construction in the rest of the country, including regions of high seismic risk, has partial grouting to make it economically competitive. However, the seismic performance of partially grouted reinforced masonry wall systems has not been sufficiently studied and is not well understood due to the complexity of their behavior, which can be attributed to the heterogeneity and anisotropy introduced by masonry blocks, block cavities, mortar joints, and grouted cells. This project is to enhance the understanding of the behavior of partially grouted masonry structures at the system as well as component level, and develop and validate economically competitive, improved, design details and retrofit methods to enhance their seismic performance...

The objective of this research project is to advance knowledge toward the development of innovative floor anchorage systems that reduce inertial forces during earthquakes and maintain a centered floor afterward. This new knowledge will be generated through a combination of analytical and experimental research, including nonlinear transient dynamic analysis, and using the equipment and tools available at two George E. Brown, Jr. Network for Earthquake Engineering Simulation (NEES) facilities: the large scale structural and hybrid testing laboratory at Lehigh University and shake table testing at the University of California, San Diego (UCSD)...

NEES-Soft: Seismic Risk Reduction for Soft-Story Woodframe Buildings

The NEES-Soft Project, whose full title is "Seismic Risk Reduction for Soft-Story Woodframe Buildings" is a five-university multi-industry collaboration has the objectives of developing and demonstrating a methodology to retrofit soft-story woodframe buildings to (1) protect life safety and property by avoiding soft story collapse and excessive upper story accelerations, and (2) provide a mechanism by which soft story woodframe buildings can be retrofitted using performance-based seismic design (PBSD) to achieve a level of performance commensurate with their stakeholders target. This will be accomplished through a comprehensive combination of new numerical modeling procedures, hybrid testing for validation of two levels of soft story woodframe retrofit ...

Analytical and Experimental Development of Bridges with Foundations Allowed to Uplift During Earthquakes

Conventionally designed bridges rely on the concept of ductility, whereby the column reinforcement is detailed to ensure the development of flexural plastic hinges at the base and the top of the columns. While bridges designed in this manner may be safe from collapse, they are susceptible to considerable damage and permanent lateral displacements that can impair traffic flow and necessitate costly, time consuming, dangerous, and disruptive inspections and repairs. As an alternative design, bridges with columns supported on rocking foundations may develop large nonlinear deformations when subjected to strong shaking ...

Earthquake Performance of Large-Scale MSE Retaining Walls

The use of Mechanically Stabilized Earth (MSE) walls in civil engineering construction has become an increasingly popular alternative to conventional gravity and semi-gravity retaining walls over the last several decades. The low cost and ease of construction of MSE walls, combined with their excellent performance record, are well-suited for many applications. Extensive research has been conducted to characterize the behavior of MSE walls under seismic loading; however, these tests have necessarily used reduced-scale models due to the limited weight capacity of small shaking tables and geotechnical centrifuges...

In the United States, about 200-300 million tires are scrapped annually. Many of them had been stockpiled in landfills, which caused serious public health problems as well as environmental issues. These days, most developed countries prohibit legal and illegal stockpiling of scrap tires and promote recycling and recovering materials. Tire Derived Aggregate (TDA) is an engineered product made by cutting scrap tires into 5 to 450mm pieces to be used in civil engineering applications as lightweight aggregates. Unfortunately, seismic issues related with TDA backfill have not been addressed thoroughly since the development of TDA in the 1990's. The distinct mechanical properties of TDA from conventional backfill materials, particularly lightweight and compressibility, must be factors that influence seismic behavior of retaining walls.

The present research aims at establishing a reliable foundation for seismic design and assessment of TDA backfilled retaining walls through numerical and experimental investigations...

Shake-Table Tests of a Two-Story Reinforced Masonry Shear Wall System

A full-scale, two-story, fully-grouted, reinforced masonry shear wall system will be tested on the NEES outdoor shake table at the Englekirk S-tructural Engineering Center of UCSD. This will be the second and also the last structure to be tested on the shake table in a research project sponsored by NIST under an ARRA Measurement Science and Engineering Grant. The project is to study the seismic performance of fully-grouted reinforced masonry shear-wall structures, and to develop improved design methodologies, detailing requirements, and analytical methods for the design and performance assessment of these structures...

Full-Scale Structural and Nonstructural Building System Performance during Earthquakes & Post-Earthquake Fire

To date, only a handful of full-scale building experiments have been conducted. Of these, none have evaluated the post-earthquake fire performance of the complete building system and only select (in Japan) have they emphasized evaluating nonstructural component and system (NCS) response during earthquake shaking. This belies the fact that NCSs encompass more than 80% of the total investment in building construction and over the past three decades, the majority of earthquake-induced direct losses in buildings are directly attributed to NCS damage.

This landmark project involves earthquake and post-earthquake fire testing of a five-story building built at full-scale and completely furnished with NCSs, including...

Current code provisions and strength design methods for reinforced masonry shear-wall structures do not adequately distinguish the unique design requirements and performance characteristics of high-rise and low-rise masonry shear wall systems of different configurations. Moreover, current seismic design provisions for masonry structures are force-based with overlays of prescriptive requirements, some of which are neither practical nor rational and have not been substantiated with experiment research. This research...

Large-Scale Validation of Seismic Performance of Bridge Columns

The seismic behavior of full-scale bridge columns designed based on current Caltrans practice is being investigated using the UCSD shake table as part of an extensive test program with E-Defense (Japan) and UC Berkeley in an effort to improve current bridge design and analysis practices.

NEESR-II A Seismic Study of Wind Turbines for Renewable Energy (WTRU)

The amount of electricity produced from the wind has steadily grown since its introduction in the 1980s and with the introduction of AB 32 is poised to grow substantially in California. Through support from the United States National Science Foundation (NSF) and specifically via the Network for Earthquake Engineering Simulation (NEES) and Oak Creek Energy Systems (OCES), a Gigawatt Wind Energy pioneer, a multiyear investigation into the seismic behavior of wind turbines is underway at the University of California, San Diego (UCSD).

This original research started with a forced and ambient vibration monitoring program at Oak Creek Energy Systems (OCES) with the assistance...

Seismic Design Guidelines of Retaining Walls with/without Sound Wall

The objective of the research project on retaining walls is to develop improved and validated rational guidelines for seismic design of retaining walls to overcome the drawbacks in the existing Caltrans design specification and tools. The research work involves 2 separate validation tests on two full-size retaining walls (each wall is about 8.5 feet long and 6 feet high Type 1 Semi-Gravity Reinforced Concrete Cantilever Wall, with a total height of 7.5 feet including a 1.5 feet thick bottom footing).

The first test includes one retaining wall without sound wall and the second test includes a sound wall on top of the second retaining wall. The walls will be backfilled...

Researchers of UC San Diego conducted shake table tests on a 3-story, non-ductile, masonry-infilled, reinforced concrete frame representing structures built in California in the 1920's. The tests on the 2/3 scale specimen are part of the collaborative project between University of Colorado at Boulder, Stanford University and University of California San Diego, which is the lead institution. The research project is funded by the George E. Brown Jr. Network for Earthquake Engineering Simulation (NEES) and is already in its 4th and final year.

The goal of the research team led by Benson Shing, a UCSD structural engineering professor, is to develop and implement analytical tools to assess the seismic vulnerability...

Seismic Design Methodology for Precast Building Diaphragms

A one-half scale three story precast concrete diaphragm will be tested on the shake table at UCSD to investigate the behavior of long-span precast concrete diaphragms under seismic excitation. The project is funded by NSF GOALI and is being conducted by a multi-university and industry consortium.

This is a landmark test funded by NSF GOALI, the Precast/Prestressed Concrete Institute and the Charles Pankow Foundation. This project will assess the behavior...

Performance-Based Design of Masonry and Masonry Veneer

Researchers at UT Austin, Washington State University, North Carolina A&T State University, and the University of California at San Diego conducted a coordinated experimental and analytical study, intended to investigate the seismic performance of wood-stud construction with clay masonry veneer, and of reinforced concrete masonry construction with clay masonry veneer, designed according to current building codes.

Seismic Response of a 7-Story RC Building

The objective of this research program was to verify the seismic response of reinforced concrete wall systems designed for lateral forces obtained from a displacement-based design methodology. A 7-story full-scale slice of a reinforced concrete residential building with cantilever structural walls was tested on the UCSD shake table. The project was funded by the Englekirk Board of Advisors, an industry group supporting research at the Charles Lee Powell Structural Laboratories at the University of California, San Diego.

The Large High-Performance Outdoor Shake Table is supported in part by the George E. Brown, Jr. Network for Engineering Simulation (NEES) program of the National Science Foundation under Award Number CMMI-0927178.